1. Field of the Invention:
The present invention relates to receiving apparatus of a vehicle and, more particularly, to a receiving apparatus using a conductor attached to a window glass as a diversity receiver antenna.
2. Description of the Prior Art:
It is known to deposit a transparent conductive film such as ITO and SnO.sub.2 films for heat wave reflection on a window glass so as to enhance a low-temperature insulating effect in a vehicle. In addition, it is known to use this transparent conductive film as a heating conductor for defogging and as an antenna conductor in a rear window.
In a receiving apparatus using such a transparent conductive film as a heating conductor and an antenna conductor, tuning is difficult, and an excellent receiving function cannot be obtained in terms of a gain (sensitivity), directivity, a frequency characteristic, and the like. For this reason, it is proposed to form an antenna conductor pattern by limiting a heating area for defogging substantially to a central portion of the entire glass surface and printing and baking a silver paste on a blank area where no transparent conductive film is formed.
As is known, in an antenna obtained by printing/baking, its wiring pattern can be satisfactorily tuned to a specific broadcast wave band (AM, FM, or the like), and an excellent receiving performance can be obtained. However, since a portion having no transparent conductive film is formed on the surface of a glass window, a heat wave reflecting function is degraded. Furthermore, if a conductive pattern with a high line density is formed, visibility is degraded, and hence the field of vision is interfered.